1. Field of the Invention
The present invention relates to an air bag apparatus disposed in an instrument panel arranged in front of the passenger's seat in a vehicle. More particularly, the present invention is directed to an air bag that has a sheet for splitting the inside of a sac-like air bag main body into a plurality or chambers, the sheet having a communicating hole.
2. Description of the Related Art
An air bag employing a sheet that splits a sac-like air bag main body into two chambers and that has a communicating hole has been disclosed in Japanese Patent Publication No. Hei. 6-191370. An air bag of this type is characterized in that not only inflation of the air bag can be completed quickly but also reduces the instantaneous moving speeds of the parts of the air bag up to the completion of inflation.
However, in the air bag disclosed in the aforementioned publication, the sheet is sewn to the inner circumferential surface of the air bag main body all along the periphery of the sheet.
In some cases the air bag main body has a sac-like shape with a circumferential wall portion that extends in a sleeve-like form from the peripheral edge of an inflating gas introducing opening to a bottom wall portion that closes the circumferential wall portion. If the entire periphery of such a sheet is sewn to the air bag main body from the peripheral edge of the opening to the bottom wall portion via the circumferential wall portion, the seam between the circumferential wall portion and the sheet wrinkles and becomes bulky at the time of folding the air bag and placing the folded air bag in the air bag apparatus. As a result, the air bag is hard to fold into a compact form.
In addition, since the sheet must be sewn all along the periphery thereof, the sewing operation is time-consuming, which in turn increases the number of manufacturing steps and air bag manufacture costs.